Numerous lighted keyboard devices have been patented and described attempting to overcome the problem with locating key board keys and switches for various electronic equipment. These prior art devices are useful for their stated purposes but they do not provide a keyboard lighting system as the present which varies the light intensity of the keyboard keys depending upon the ambient light conditions. The present invention automatically adjust the light intensity of the lighted keyboard keys by use of a circuit which is operated by a photosensitive transistor which provides more voltage in a inverse relationship to the ambient light to small grain of wheat type lamps located adjacent to the keys on the key board. In addition to having circuitry controlling light intensity conditions, the present invention also includes a novel placement of small grain of wheat type incandescent lamps embedded adjacent the key board keys. Light from the small grain of wheat type lamps are transmitted through fixed clear plastic mounting blocks to lower edges of the moveable translucent plastic keyboard keys. The inside surface of the translucent keys are coated with a reflective metallic coating increasing the reflective qualities of the translucent keys. Additionally, the present invention includes a manual keyboard light intensity switch allowing a user to increase the intensity of the keyboard illumination if desired.
The prior art patents which are relevant include the following:
Shima, U.S. Pat. No. 5,669,486; Park, U.S. Pat. No. 5,568,367; Larose, U.S. Pat. No. 5,512,718; Muurinen, U.S. Pat. No. 5,408,060; Murphy, U.S. Pat. No. 5,391,848; Demeo, U.S. Pat. No. 5,149,923.
As can be seen from reviewing the prior art, there has never been an invention as the present which includes the keyboard key illumination system that is variable in intensity depending upon ambient light conditions wherein the keypad light intensity circuitry is controlled by a photosensitive transistor located on the keyboard frame and wherein said photosensitive transistor increases voltage to small grain of wheat type incandescent lamps when ambient light conditions are lowered, furthermore, the small grain of wheat type lamps are positioned adjacent to the individual keys in translucent plastic mounting block so that the lights transmit light through fixed plastic mounts to an edge of each keypad, the keypads are translucent plastic keys which side edges engage the fixed plastic mounts thereby allowing light to be transmitted into the translucent keypad material and further wherein the keypad material includes a reflective back coating providing efficient reflective qualities and thereby increasing the light intensity emanating from the keypad. The device also includes a manual light intensity switch which allows a user to increase the light intensity of the keypads if desired.